1. Field of the Invention
The present invention relates to vehicles with a clutch for transmission of torque output of a motor.
2. Description of the Background Art
Vehicles are known which include a prime mover in the form of, such as, an internal combustion engine, drivingly coupled to a first set of road wheels, a motor, and a clutch to engage and disengage the motor to and from road load from another set of road wheels. Publications disclosing such vehicles are Japanese Published Patent Applications (JPPA) Nos. 11-243608 (published Sep. 7, 1999), P2000-318473A (published Nov. 21, 2000), P2002-160541A (published Jun. 4, 2002), and P2002-171605A (published Jun. 14, 2002).
JPPA No. 11-243608 discloses a vehicle with a motor control. According to this control, a dog clutch is engaged to couple a motor to road wheels after motor speed has matched the wheel speed. JPPA No. P2000-318473A discloses a vehicle in which, a generator supplies energy to a motor that is selectively coupled to road wheels by a dog clutch. JPPA No. P2002-1 60541A discloses a vehicle with a motor control According to this control, a hydraulic actuator engages a clutch after motor speed has sufficiently approached to the wheel speed. JPPA No. P2002-171605 discloses a vehicle in which engagement force of a clutch is variably controlled in response to state of charge of an energy storage device when a measure of vehicle speed is not less a preset value. The clutch is completely engaged when the measure of the actual vehicle speed is less than the preset value.
An object of the present invention is to provide a vehicle, which provides extended operating range of a motor as well as providing protection to the motor.
Another object of the present invention is to provide a method for and an apparatus for providing extended operating range of a motor as well as providing protection to the motor.